* {
    box-sizing: border-box;
}

body {
    margin: 0;
    font-family: 思源黑体;
}

.display {
    display: flex;
    flex-flow: column;
    align-items: center;
}

.word {
    display: flex;
    margin: 2em 0;
}

.pair {
    margin: 0 0.5em;
    text-align: center;
}
.pair > .pinyin {
    color: peru;
    font-weight: lighter;
}
.pair > .character {
    display: flex;
    justify-content: center;
    align-items: center;
    margin-top: 0.2em;
    width: 1.2em;
    height: 1.2em;
    line-height: 1em;
    font-family: 思源宋体;
    font-size: 2em;
    font-weight: 1000;
    border-style: solid;
    border-width: thin;
    border-color: peru;
}
.explanation {
    padding: 0 2em;
}
.answer {
    display: flex;
    margin-top: 2em;
    width: 100%;
    height: 2em;
}
.answer > .score {
    display: flex;
    justify-content: center;
    align-items: center;
    flex-shrink: 0;
    position: absolute;
    padding: 0 0.4em;
    height: 2em;
    border-style: solid;
    border-width: thin;
}
.answer > .input {
    flex-shrink: 1;
    width: 100%;
    height: 100%;
    text-align: center;
    font-size: 1em;
    outline: none;
    border-style: solid none;
    border-radius: 0;
    -webkit-appearance: none;
}
.answer > .submit {
    display: flex;
    justify-content: center;
    align-items: center;
    flex-shrink: 0;
    position: absolute;
    right: 0;
    padding: 0;
    width: 2em;
    height: 2em;
    font-size: 1em;
    background-color: green;
    border-radius: 0;
    border-style: none;
    -webkit-appearance: none;
}
.answer > .submit > img {
    height: 100%;
    width: 100%;
}

.bar-box {
    width: 100%;
    height: 5px;
    background-color: red;
}
.bar {
    height: 100%;
    background-color: green;
    transition: all 0.25s linear;
}
.pasts {
    padding-top: 1.5em;
    display: flex;
    flex-wrap: wrap-reverse;
    justify-content: center;
    flex-direction: row-reverse;
    align-items: center;
}
.pasts > .past {
    cursor: pointer;
    margin: 0.5em 0.5em;
    padding: 0.2em 0.5em;
    background-color: #eee;
    border-radius: 0.3em;
    transition: all 0.2s;
}
.pasts > .past:hover {
    transform: scale(1.1);
}
